Automatic test apparatus for phase comparison protective relay systems and the like

ABSTRACT

Apparatus for automatically testing protective relay system as utilized with high voltage transmission lines, the apparatus consisting of a master control unit, at a first terminal working in conjunction with one or two slave control units at adjacent terminal stations. Each of the master and slave control units are controlled through a cycle of actuation by a synchronous timer means such that a programmed series of switch closures performs a test of associated transmission and reception equipment and the respective protective relay devices to transmit starting signal, ring back, internal and external simulated faults and a selected security code. Each test control unit utilizes a time-controlled program switch which is synchronously operable to effect various test and verify operations in the control unit.

United States Patent Marion D. Knox Oklahoma City, Okla. 812,770

Apr. 2, 1969 Sept. 28, 1971 Inventor Appl. No. Filed Patented Aimignee Wayne Electronic Products Company AUTOMATIC TEST APPARATUS FOR PHASE COMPARISON PROTECTIVE RELAY SYSTEMS Primary Examiner-Rudolph V. Rolinec Assistant Examiner-R. J. Corcoran Attorney-Dunlap, Laney, Hessin & Dougherty ABSTRACT: Apparatus for automatically testing protective relay system as utilized with high voltage transmission lines, the apparatus consisting of a master control unit, at a first terminal working in conjunction with one or two slave control units at adjacent terminal stations. Each of the master and slave control units are controlled through a cycle of actuation by a synchronous timer means such that a programmed series of switch closures performs a test of associated transmission and reception equipment and the respective protective relay devices to transmit starting signal, ring back, internal and extemal simulated faults and a selected security code. Each test control unit utilizes a time-controlled program switch which is synchronously operable to effect various test and verify operations in the control unit.

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2. Description of the Prior Art Prior methods of testing of protective systems for high voltage transmission networks have been carried out manually by performance of prescribed operator manipulations and subsequent observations of meter readings, lamp indications, etc. In the prior types of protective relay systems, which may include either carrier-current or microwave equipment, it has been the general practice to make carrier transmission tests at specified intervals, for example, once per day. To accomplish this, it required that an operator at each terminal station send and receive specific signals, and that they thereafter log the pertinent findings as read from the respective receiver equipment, i.e. the normal, the reserve-signal or reduced power values, and whatever other standardized values as were. received in accordance with the test program.

SUMMARY OF THE INVENTION The present invention contemplates an interlinking carrier and relay testing system which can be installed at each terminal of a high voltage transmission network to carry out periodicchecks upon the protective relay system by means of a programmed, sequence of carrier transmission and reception checks as between the two or three terminal installations. In a more limited aspect, the testing system is comprised of a plurality of switching systems, each of which is controlled by a periodically actuated program switch to control the several functions of the carrier and relay equipment at each terminal. Thus, at each tenninalin the protective relay system, two or three terminals or transmission line substations being the normal situation, there is an automatic test unit consisting of a programming switch which controls a plurality of switching assemblies to efiect carrier output, verification ring back, presence or absence of simulated internal and external faults and security code, lockout of units, testing stop notice, and alarm functions in accordance with the test procedure as programmed.

Therefore, it is an object of the present invention to provide apparatus for automatically testing the carrier, the static relays and the control units in a high voltage surveillance network.

It is also an object of the invention to provide a system which enables periodic automatic testing of all functions of an electrical current transmission line protective relay system as utilized with either a carrier or microwave interconnection.

It is still a further object of the present invention to provide a phase comparison protective relay testing system which is programmable as to the sequence and type of test functions between terminals.

Finally, it is an object of the present invention to provide an automatic static relay testing system for use with either carrier or microwave systems which is compact, lightweight, and virtually trouble-free as regards maintenance problems.

Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawings which illustrate the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a block diagram of power terminal interconnection utilizing test apparatus in accordance with the present invention;

FIG. 2 is a block diagram illustrating various possible modes of application of the present invention to electrical power distribution networks;

FIG. 3 is a block diagram of one form of terminal installation utilizing the present invention;

FIG. 4 is a schematic diagram of master terminal testing circuitry;

FIG. 5 is a schematic diagram of one form of interconnection circuitry as utilized in one form of the invention;

FIG. 6 is a partially schematic illustration of a program switch as utilized in the present invention;

FIG. 7 is a schematic diagram of a remote testing terminal constructed in accordance with the invention;

FIG. 8 is a program diagram which may be utilized in a two terminal testing system;

FIG. 9 is a program diagram which may be utilized in a three terminal testing system; and

FIG. 10 is a block diagram illustratingthe use of the present invention for testing an alternative form of relay interconnecting system.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates a typical form of electrical power transmis sion line with transmission proceeding from a source 10 to a power terminal 12 and power terminal 14 to a consumer 16. Control surveillance of the transmission system includes electronic transmission equipments l8 and 20 interconnected at the respective power terminals 12 and 14 and in communication via a linkage 22, e.g. wireless, coaxial cable, microwave transmission, pilotwire, etc. As regards the power tenninals l2 and 14, powerline faults occurring'between stations in the area 24 would be designated internal faults, while line failures occurring in either of areas 26 or 28 would be termed external faults. It should be understood too that the terminal configuration may be variously interconnected as shown in FIG. 2, as will be described.

The transmission equipment 18 functions with power terminal 12 in response to a control unit 30 which is interactively operable with an automatic test apparatus 32 and a protective relay 34 to effect the required safety cautions through line switching by control of terminal circuit breakers (not shown). Similarly, the transmission equipment 20 at power terminal 14 is controlled by a control unit 36 functioning with an automatic test apparatus 38 and protective relay 40. Fault indications are derived from line voltage or current sensing at respective power terminals 12 and 14 via lines 42 and 44' for application to control units 30 and 36, respectively. One terminal may be designated as central and it will then include an alarm and central control 46 for regulating the automatic test system as is carried out by the automatic test apparatus 32 and Y 38, to be further described.

the type and number of interconnections is practically unlimited. Thus, a power generator 50 supplies electrical power via line 52 to terminal 54 which performs various functions in different interconnections as regards its automatic test capabilities. Thus, terminals 54, 56 and 58 constitute a three terminal power network wherein terminal 54 is the master or A terminal while terminals 56 and 58 are slave, or respective B and C terminal automatic testing stations. A two terminal network is formed by terminals 54 and 60 with terminal 54 still being the master or A terminal while terminal 60 is a B terminal testing station. A similar two terminal automatic testing network is formed by tenninal 58 as master A terminal anda terminal 62 as a remote or slaved B terminal.

Interconnection of still another power generator or source 64 gives rise to further integration of the power grid. Thus, a terminal 66 may be a master terminal for both of terminals 68 and 70. Each of the terminals 68 and 70 is then a slaved remote terminal responding to automatic test control functions as initiated from the A terminal 66. In similar manner, terminals. grid interconnection between terminals 66 and 54 might find terminal 54 slaving to automatic test function output from the A terminal 66. Any number of terminals through various interconnections are possible with but minor alterations in test programs as will be further described in detail.

While the present invention can be utilized to test various forms of carrier and microwave equipment utilizing any of several types of protective relay line control, the invention is particularly described herein with respect to a phase comparison relay system 80 as employed at a breaker 82 along high voltage power transmission lines 84, 86 and 88. The phase-comparison relay system 80 is a standard protective equipment such as is commercially available from the Westinghouse Electric Corp. of Newark, N. J. The phase-comparison relay system 80 may consist of a control unit 90 and a relay unit 92 functioning with a carrier equipment 94, i.e. a transmitter 96 and receiver 98 operating through a selected transmission line 100.

The relay unit 92 consists of a sequence network 102 which is connected to sense currents in the respective power transmission lines 84, 86 and 88 to derive a matrix output for application to a high-low fault detector 104. Fault detector 104 then provides a high-set output 106 and a low-set output 108 for control purposes as will be further described. A trip coil 1 10 controls tripping of the power line circuit breaker 82.

The control unit 90 receives control output from sequence network 102 via input 110, a sixty cycle half-wave voltage, which is supplied through a low pass filter 112 to a terminal 114. Voltage at terminal 114 is then applied on a line 116 to modulate the carrier transmitter 96 when applied in coincidence with a low-set output on lead 108 from fault detector 104. Keying of the carrier transmitter 96 then provides carrier output via transmission line 100.

The voltage from junction 114 is also applied through a local amplifier 118 which includes phase delay with input to a phase comparison circuit 120. Sixty cycle half-wave pulses from a remote tenninal are received via transmission line 100 to carrier receiver 98 whereupon its output is conducted through a remote amplifier 122 for application to phase comparison circuit 120. The output of phase comparison 120 is effectively a comparison of the local voltage on line 124 and a remote voltage on line 126 to derive a trip voltage on line 128. If the phase comparison 120 indicates in-phase voltages on leads 124 and 126, an internal fault is existent, and output on lead 128 is applied through a time delay 130 to a flip-flop 132 which actuates a trip amplifier 134. The high-set output from fault detector 104 on lead 106 is applied to enable the flip-flop 132. Output from trip amplifier 134 is them applied on line 136 to the tripping relay 138.

An automatic test apparatus 140, the subject of the present invention as will be further described, is interactively connected with each of the carrier transmitter 96 and carrier receiver 98, as well as sequence network 102 and the tripping relay 138. The automatic test apparatus 140 functions with an auxiliary relay 142, periodically, to check selected terminals of the relay carrier system including such as the associated control unit 90, relay unit 92 and carrier set 94. While the structure of FIG. 3 represents equipment at a single terminal of a power transmission line, it should be understood that similar apparatus will be located at each terminal, and that the automatic testing system will function between terminals in selected combinations of two or three.

Referring now to FIG. 4, an automatic test unit 150, a master of A terminal tester, is interconnectable by means of terminal boards 152 and 154 into an associated relay system. The interconnection diagram of FIG. illustrates such interconnection connection from respective terminal boards 152 and 154 to the specific components of the control unit, relay unit, and carrier set. An interconnection circuit 156, as shown in FIG. 5, receives llS-volt AC line input via leads 158 and 160 for application in parallel to terminals 162 and 164 of terminal board 154, as well as to a primary coil 166 of a test transformer 168.

With further reference to terminal board 154, a terminal 170 is connected to a lead 172 which is connected to telephone hand set unit 174 with return to a negative l25-volt DC lead 176. The negative l25-volt DC lead 176 leads up to voltage input terminal 178 as well as to a terminal 180 on terminal board 152. Positive voltage of volts DC is applied at .terminal 181 for distribution throughout interconnecting unit 156 via voltage lead 182, the lead 182 also connected to a terminal 184 of terminal board 152. A tenninal 186 of terminal board 154 is connected through a conductor 188 to an alarm bell 190, and the alarm bell 190 is energized by means of carrier receive relay contacts 192 which connect to the plus DC voltage lead 182. The relay contacts 192 are energized closed upon energization of carrier receive relay 94 which is connected for actuation between carrier receiver 196 and the minus DC voltage lead 176. The plus DC side of the alarm bell 190 is connected by means of a lead 198 to a terminal 200, the carrier receive terminal, of terminal board 152.

Returning again to terminal board 154, a tenninal 202 is connected to a lead 204 in series with a normally closed automatic test disable switch 206 which leads back to terminal 208. A tenninal 210 connects to a lead 212 in series with a secondary 214 test transformer 168 with return via lead 216 back to a terminal 218 of terminal board 154. Terminals 220 222 are each connected to respective leads 224 and 226 which are connected to the primary of a saturation transformer 228. Saturation transformer 228 includes a phased array of control transformers in inductive relationship to the power transmission line and it serves to pick up and present any fault currents during fault conditions.

Terminals 230 and 232 provide connection to an alarm output 234 for efiecting a suitable form of alarm actuation. Terminals 236 and 238 provide flip-flop reset energization as terminal 236 is connected through a reset switch 240 and it normally open fault detector contact 242 to a reset contact 244 which is located on the control unit flip-flop circuit (e.g. flipflop 132 of FIG. 3). The remaining terminal 138 is connected by means of a lead 246 to a flip-flop power supply 248.

Referring again to secondary terminal board 152, a terminal 250 is connected through a conductor 252 to a pair of normally open contacts of the auxiliary relay 142. Terminal 256 is connected directly to one side of relay coil 258 of auxiliary relay 142 with return to the negative DC voltage lead 176. The nonnally closed contacts of auxiliary relay 142 are connected in parallel to a lead 260 which leads to the trip coil 110 (FIG. 3) which is returned through negative DC voltage lead 176, and the lead 260 is also applied through a backup relay 264 to the positive DC voltage lead 182. A lead 266 from the parallel-wiper contacts of auxiliary relay 142 is connected in series through a suitable trip indicator 268 and alarm relay contact 270 with return to the positive voltage lead 182. The remaining terminals 274 and 276 of secondary terminal board 152 are connected to a transmitter keying circuit 278 which effects control of the carrier or such transmitter equipment which is associated with the particular terminal installation.

Returning again to FIG. 4, the master or A terminal test unit is energized by AC line input at tenninals 162 and 164, and energization is enabled by a start switch 289 which applies the AC line voltage across a synchronous timing motor 282. The synchronous timing motor 282 may by any of various commercial types which include an associated gear box (not specifically shown) for reducing output rotation to a low rate of angular advancement. Thus, in one form of the invention, it is found desirable to employ a programmable timer motor 282 which effects closure of a timer switch 284 periodically. This timing or the frequency of closure of timer switch 284, can be varied in accordance with the exigencies of particular equipment applications.

The start switch 280 applies the AC line voltage through a lead 288 to test board terminal 208 for circuit through the automatic test disable switch 206 (FIG. 5) for return through terminal 202 and a lead 290 to an AC energizing lead 292. When the timer switch 284 is closed, the AC energizing voltage from lead 292 is applied through an energizing coil 294 of time delay 296 with return to the other side of the AC line, a lead 298 to terminal 164. AC voltage from junction point 300 is conducted through time delay switch contacts 302 for a period of about 10 seconds and through a lead 304 to one side of a programming motor 306. AC initiation to lead 304 is also I conducted through a suitable form of counter 308 with return through the remaining AC lead 298 to provide a testing tally.

The programming motor 306 effects program control of a plurality of program switches 310, 312, 314, 316, 318, 320, 322, 324, and 326. The program switch 310, the test cycle program switch, will be held in the open position (opposite that shown) when the test unit 150 is in its standby or quiescent state. Starting of rotation of program motor 306 upon closure of timer switch 284 will then allow closure of the test cycle program switch 310 to supply energizing AC voltage from lead 292 through a lead 328 and 330 to maintain cnergization of the program motor 306. It may also be noted that a manual test switch 332 is provided to enable an operator to initiate a test cycle at other than times dictated by timer motor 282 and timer switch 284. Depression of pushbutton switch 332 will apply AC voltage from lead 292 onto lead 304 to energize the program motor 306.

FIG. 6 illustrates one form of program motor 306 as it may be associated with suitable programming structure. A motordriven program switch 334 is similar to structure which is fully disclosed in 11.8. Pat. No. 3,414,773, also assigned to the present assignee. The program switch 334 embodies a unique design which enables easy variation of the switch program. That is, a program drum 336 is divided into sixty equal, arcuate segments arrayed about its circumference, there being a groove 338 between each segment such that plastic placers or inserts 340 can he slid into the grooves 338 and aligned with particular ones of the leaf switch actuators (switches 310 through 326) thereby to construct a desired relief or switch actuating structure. Thus, any program desired may be set into the program switch simply by adding or removing the plastic spacers 340 at the given program positions, i.e. a circumferential path in alignment with a particular one of the switches 310 through 326. In the prototype equipment, the test units 150 employ motor 306 and gearing (not specifically shown) which generate one revolution per minute such that each segment of the program drum 118 is equal to I second in time.

Each of the program switches 310 through 326 performs a specific function through each 1 minute test cycle or revolution of the program drum as provided by program motor 306. Thus, the test cycle program switch 310, a normally closed switch is allowed to remain in its closed position, (as shown to provide holding energization to the program motor 306 through its entire 1 minute cycle. At the end of the cycle, a single program spacer 340 is engaged to open the switch 310 and stop the revolution of the program motor 306. A program switch 312, the open alarm bell switch, is normally closed to provide a connection between leads 342 and 344 to terminals 170 and 186 of terminal board 154. When actuated, program switch 312 connects the lead 342 to lead 346 which provides energizing connection to a relay 348 when certain additional enabling conditions are met, as will be further described. Program switches 314 and 316 are designated change polarity" switches as they serve to reverse the polarity of voltage at test transformer contacts 210, 220, 222 and 218. The terminals 220 and 222 are connected via leads 350 and 352 to the respective wiper contacts of switches 314 and 316. Switch connections are then alternated between leads 354 and 356 which, when relay 348 is actuated to close contacts 358 and 360, are connected to respective leads 362 and 364 leading to terminals 210 and 218.

The open trip circuit" program switch 318 is in a normally open position with wiper lead 366 leading to the auxiliary relay" terminal 256 of terminal board 152; a parallel branch of lead 366 also provides connection to the. relay coil 348. Upon actuation, program switch 318 is closed for connection to a lead 368 through a relay contact 370 and lead 372 to the plus l25-volt DC source or terminal 184 of terminal board 152. The nest program switch 320 serves a verify local alarm and trip function and it is normally open but actuated closed to connect the AC voltage lead 292 to a lead 374.

A green lamp 380 is energized by lead 328 from program switch 310, i.e. in parallel with program motor 306, such that it indicates the test cycle on that time when program motor 306 is running. A blue indicator bulb 382 is connected for energization between one of the relay trip terminals 250 and the negative DC voltage terminal 180 of terminal board 152, and this blue indicator 382 is energized in response to a trip condition switched through the auxiliary relay coil 258 (FIG. 5), as connected via lead 383 to terminal 250. A red indicator lamp 384, the alarm indicator, is energized to indicate the alarm condition as will be further described below. The lamps 380 and 384 may be standard AC indicator bulbs while the blue lamp 383 is a DC lamp having a suitable resistance value.

A terminal trip relay 386 is connected in parallel with the blue indicator 382 and it is energized during the trip" condition to control the relay contact 388 such that lead 374 from program switch 320 is removed from connection to a lead 390 which provides energization to the red alarm" indicator lamp 384. This removable of connection between lead 374 and lead 374 and lead 390 also disables the posibility of energization of an alarm relay 392 under control of the verify local alarm and trip" program switch 320. Alarm relay 392 controls a plurality of contacts 370, 394 and 396. Contacts 394 are normally open as between the alarm output terminals 230 and 232 of terminal board 154; and relay contacts 396 are normally open between the voltage source lead 390 and a lead 398 in series with a normally closed reset" switch 400 i.e., conventional pushbutton type of switch which is returned to the AC lead 292.

A carrier receive relay 402, connected between the negative voltage terminal 180 and the carrier receiver terminal board 200 of terminal board 152, is energized in response to closure of relay contacts 192 of carrier receive relay 194 (FIG. 5). The carrier receive relay 402 controls relay contact 404, a normally closed contact, to open up electrical contact between lead 374 from program switch 320 and a lead 406 connected to the normally open contact of relay contact 388 of the relay 386. A parallel connection of lead 406 is also applied to the wiper contact of the verify remote alarm program switch 322.

Alarm output at tenninals 230 and 232 of terminal board 154 is provided from relay contacts 394 by respective leads 408 and 410. The alarm output would be in the fonn of a switch closure at relay contact 394. The test reset output at terminals 236 and 238 is provided from the "reset" program switch 324 via leads 412 and 414, respectively. Closure of the carrier start" program switch 326 provides switch actuation through terminals 274 and 276 of terminal board 152 to the transmitter keying circuit 278 (FIG. 5).

FIG. 7 illustrates a B or C terminal, or a remote test unit which functions in coaction with the master test unit 150 to carry out the system test. The remote test unit 420 is generally similar to the master test unit 150, but it is characterized by absence of some master control components. Thus, primary and secondary terminal boards 422 and 424 provide all interconnection contacts. The terminal board 422 provides volt AC line voltage input at terminals 426 and 428, and the terminals 430, 432 and 434 provide respective connections for hand set," alarm bell," and test disable." The test transformer connections, four in all, are applied at contacts 436, 438, 440 and 442, and a second test disable" connection is made at contact 444. Further, contacts 446 and 448 receive alarm output" connection while a pair of contacts 450 and 452 provide the necessary test reset interconnection.

The secondary terminal board 424 receives positive and negative DC voltage supply at respective terminals 454 and 456, with carrier receive," trip input and auxiliary relay,"

connections being made at the respective terminal contacts 458, 460 and 462. In general then, the input connectionsfor the remote test unit 420 are similar to those for the master test unit 150, and a similar type of interconnection circuitry, such as is shown in FIG. 5, is employed as the interface structure.

Also, a similar type of program switch is utilized in the remote test unit 420, i.e. a program motor 464 providing output motion via dashline 466 to provide periodic actuation of the respective program switches 468, 470, 472, 474, 478, 480, 482 and 484. The program assembly consisting of program motor 464 and the plurality of switches 468-484 is preferably a drum-type utilizing the plurality of switches as described in FIG. 6, and as fully set forth in the prior issued US. Pat. No. 3,414,773 which is the property of the common assignee.

The AC energizing voltage is applied through a start switch 486 through a lead 488 and tenninal 434 to an external circuit interrupter, e.g. test disable switch 206 of the FIG. interconnection unit 156. The energizing voltage is then returned via terminal 444 and a lead 490 to a junction 492 which provides energizing voltage distribution via parallel leads 490 to fulfill several start-up functions. First, since the remote test unit 420 is started upon receipt of carrier energy from the master unit, a carrier receive relay 494 is connected via leads 496 and 498 between terminals 456 and 458, respectively, of terminal board 424, and it is energized to provide actuation of respective relay contacts 500, 502, 504 and 506. The relay contact 506 is then closed to connect AC energizing voltage from lead 490 through a relay coil 508 of time delay relay 510 to close relay contact 512 for a time delayed interval, e.g. seconds, such that energizing voltage is available on lead 514. However, relay contact 504 will also have been opened so that AC energization must proceed from voltage junction 492 of lead 390 through the test cycle program switch 468, which will have been moved to its closed or normal position (as shown), to provide AC energization along lead 516. The AC on lead 516 energizes program motor 464 to begin its constant, programming revolution to control the respective program switches 468 through 484. The other side of program motor 464 is returned by a lead 518 and a lead 520 to the other side of the AC input at terminal 428. A green indicator lamp 522 is connected between the energizing lead 516 and the AC lead 520 to provide lamp energization during the test cycle.

Program switch 470, the lockout switch, is actuated to make connection between the AC energizing lead 516 and a lead 524 to the normally closed position of relay contact 502 of the carrier receive relay 494. The wiper connection of relay contacts 502 is connected to a lead 526 and alarm indicator 528, a red lamp, with return to AC lead 520. The test key" program switch 472 provides the functions of opening the alarm bell circuit and keying the test source. The wiper position is connected to a lead 530 leading to terminal 430, the handset terminal of terminal board 422. The normally closed contact is connected by a lead 532 to the alarm bell terminal 432 of the terminal board 422, and the normally open contact connects by a lead 534 to relay 536 which is returned by means of a lead 538 to the relay trip terminal 462 of secondary terminal board 424.

The program switches 474 and 476 combine to carry out the "change of polarity function with respect to the test voltage. Thus, a test voltage present at terminals 436 and 442 via leads 552 and 554 is supplied through relay 536, Le. contacts 548 and 550, to the respective program switches 474 and 476. The wiper input positions of contacts 548 and 550 are then connected to leads 552 and 554 which are connected to the respective test transformer terminals 436 and 442.

The program switch 478 functions to open the trip circuit and it is nonnally open with one contact connected to a lead 556 and the wiper contact connected to the lead 538 which is connected to auxiliary relay terminal 462. Lead 556 is connected through a relay contact 558 which is normally closed to receive positive DC voltage via lead 560 from terminal 454. The verify local alarm and trip" switch 480 is normally open but actuated closed to connect AC voltage from energization lead 516 through a lead 562 which is connected in parallel to normally closed relay contact 500 as well as to a contact 564 of a relay 566. Relay 566 is connected via leads 568 and 570 between terminals 456 and trip input terminal 560. A blue indicator lamp 572, a DC lamp, is connected in parallel with the coil of relay 566 to indicate the trip" condition when relay 566 is energized.

The program switch 482 functions to verify remote alarm with no trip condition, and it is normally open but actuatable to connect the AC energizing lead 516 to a lead 574. Lead 574 connects to the common or wiper position of relay contact 500 as well as to the normally open position of relay contact 564 of the relay 566. Finally, the program switch 484 carries out the reset function as it is normally closed to provide short circuiting between leads 576 and 578 which are connected the test reset terminals 450 and 452 of terminal board 422.

An alarm relay 580 is connected between lead 526 and the AC lead 520 and it is energized to provide several control functions. The contact 558, which is normally closed to conduct positive DC voltage from terminal 454 and lead 560, is opened to prevent energization of relay 536 or DC output to the auxiliary relay 142 (FIG. 5) via 462. A normally open relay contact 582 may be energized to complete the alarm circuit between leads 584 and ,586 to the alarm output terminals 446 and 448 of terminal board 422. The remaining relay contact 588 is normally open and energized closed to connect the AC energizing lead 516 to the intermediate energizing lead 526 which includes holding energization of the alarm" indicator lamp 528 and relay 580.

OPERATION The operation description is set forth with respect to a two terminal testing system, Le. a master A terminal and a remote B terminal. FIG. 8 illustrates a two tenninal program diagram for both the A and B terminals. Thus, FIG. 8 represents the circumferential field of program drum 336 (FIG. 6) which has 60 segments per complete revolution, and the plurality of horizontal black lines indicate the position of plastic spacers 340 (FIG. 6) disposed thereon for actuation of each of the respective A terminal program switches 310 through 326 and B terminal program switches 468 through 484.

It is generally the procedure to begin testing operation with the transmitters adjusted to generate some designated percentage of normal or full output, i.e. a reduced power output. This then enables what is effectively a reduced power test between the particular terminals, with full power tests and verifications effected thereafter.

Program test is initiated at the A terminal (FIG. 4) as timer motor 282 closes switch 284 to apply AC energization through time delay relay 296 to initiate rotation of program motor 306. In the off position, program motor 306 will be held deenergized by a program spacer 602 (FIG. 8) which terminates and holds off energization of the test apparatus after each test cycle. Initial energization of program motor 306 through time delay relay contact 302 is sufficient to move the program drum so that program spacer 602 no longer holds program switch 310 open, and in its closed position it maintains energization for the following 59 segments of program drum rotation. The program spacer 604 is arranged to actuate program switch 326, the carrier test circuit, from positions two through 19 such that program switch 326 keys the carrier on for 18 seconds. At position three, program switch 322 responds to a program spacer 606 to verify reception of a local alarm, absence of verification serving to stop the test in progress. The program switch 312 is actuated by program spacer 608 to hold open the local alarm bell circuit until position 19.

Meanwhile, at terminal B, carrier received indications will cause actuation of a relay 494 to close relay contact 506 such that the time delay relay 510 is energized with current conduction through the coil 508. When the relay 494 ceases conduction, after receiving at least 15 seconds of carrier on" indication, the remote program motor 464 is energized thru contact 504 and remote program switch 468 is moved out of contact with program spacer 610 such that program motor 464 (ter minal B) remains energized for the next 59 seconds of the duration of its respective test cycle. At this occurrence, the respective master and remote test units 150 and 420 are running and they are in synchronization.

It may be noted that telephone conversations, telemetering transmissions or other supervisory control transmissionsin addition to fault conditions might cause energization of a long pulse of carrier which could start the remote terminals. However, time delay relay 296 protects such that carrier transmission of less than 15 seconds is not able to start the running and synchronization of program motors at remote terminals. After starting, the remote terminal must still verify a security code before proceeding with the remainder of the test cycle.

Thus, at position 20, a master terminal program spacer 612 actuates program switch 318 to energize the related auxiliary relay 142 (FIG. Actuation of the auxiliary relay 142 opens the energizing circuit via lead 260 to the actual equipment trip coil 1 to remove effects of actuation of the alarm relay 270. Thus, conduction during simulated fault condition is from lead 266 through auxiliary relay 142 to lead 252 and terminal 250 (FIG. 5) to energize the terminal trip" relay 386 of FIG. 4. This also energizes the blue lamp 382 to indicate the trip condition.

Simultaneously, positive DC voltage is supplied from program switch 318 to the test enable relay 348. Then, when program switch 312 is keyed by program spacer 614 from positions 22 through 24 of FIG. 8, it serves to open the alarm bell circuit while energizing relay 348 to actuate contacts 358 and 360 closed so that they connect the test source potential to the static relay, i.e. the protective relay undergoing test at the particular terminal installation. In the present application, test source potential will be available on leads 350 and 352 to the terminals 220 and 222 (FIG. 4) for conduction via leads 224 and 226 (FIG. 5) to the primary of saturation transformer 228.

In the case of a phase comparison protective relay system, as is primarily disclosed in respective FIGS. 4 through 8, the low-set fault detector should operate to effect transmission of half cycle pulses from the respective carrier transmitter 96 FIG. 3), while the high-set fault detector serves to generate the local trip condition in conventional manner. The trip condition will be indicated by illumination of the blue trip lamp 382 with relay 386 energized. At the B terminal, half cycle pulses must be received at the respective carrier receiver 196 with indication to the test unit 420 when program switch 470 closes for 1 second in response to program spacer 616 at position 23, contact 502 must be actuated open or the system will alarm. The proper receipt serves to verify or effect a second portion of the security code, which, in turn, serves to keep the terminals unlocked and ready for testing.

Absence of the signal, i.e. when no half cycle pulses are received at the B terminal carrier receiver, the test unit 420 will alarm and lock out since failure to apply a carrier receive input at terminal 458 of terminal board 424 fails to energize carrier receive relay 494 to open the contact 502; and, any closure of program switch 470 will then effect the alarm condition by illuminating red lamp 528 and actuating alarm relay 580. Also in position 23, a terminal A program spacer 618 effects closure of program switch 320 to verify the trip relay 386, i.e. AC energizing voltage as applied from 292 through lead 374 and relay contact 388 to actuate the red alarm lamp 384 and the alarm relay 392. If test security is true, closure of program switch 320 serves to verify that trip relay 386 is energized and that carrier relay 402 is energized.

At the B tenninal, position 25, program spacer 620 actuates program switch 478 to effect closure of that auxiliary relay 142 (FIG. 5) which is associated with the 8 terminal. Energization of the auxiliary relay 142 (B terminal installation) opens the energizing circuit for the respective trip coil 110 to apply trip energizing power via lead 252 to the terminal 250 (FIG. 5). This, in turn, provides connection across terminal 460 of input terminal board 424 of B terminal test unit 420 such that a trip energizes the blue trip" lamp 572 and the trip relay 566. Simultaneously, as the trip is opened, the positive DC voltage is supplied to relay 536 such that, upon keying of remote program switch 472 at positions 26-28 by program spacer 622, the alarm bell circuit is opened and relay 536 is energized to connect the test source potential to the primary of the respective saturation transformer.

The remote terminal static relay then must also operate to transmit half cycle pulses of carrier and trip. Tripping will be indicated by the illumination of the blue trip lamp 572. At position 27, program switch 480 is actuated in response to program spacer 624 and this serves to verify the trip relay 566 as carrier receive relay 494 is energized. At the master A terminal, program switch 322 is closed in response to program spacer 626 at position 27 and this verifies reception of carrier from the remote terminal, but without local tripping as respects the master terminal equipment.

Program spacers 636 and 638 (remote) control respective program switches 318 and 478 which operate to open the respective trip circuits by energizing the related auxiliary relays 142 at each of the master and remote terminals.

An internal fault is simulated when master program switch 312 is keyed by program spacer 628 at positions 33 to 35, and remote program switch 472 is keyed by program spacer 630 at the same position, respective local trips being keyed thereby. The auxiliary relay 142 at each terminal passes the trip to relays 386 and 566 for verification at position 34, i.e. a plastic spacer 632 effecting program switch 320 and, at the remote terminal, a plastic spacer 634 aifecting program switch 480. Actuation of the respective program switches 320 and 480 serves to apply the AC energizing voltage to the contacts of the respective trip relays 386 and 566 thereby to verify their switch setting.

The master and remote terminals can change the phase of their respective test source potentials by keying of program switches 314 and 316 at the master terminal, and program switches 474 and 476 at the remote terminal. Thus, program spacers 640 and 642 actuate program switches 314 and 316 such that the A terminal test voltage phase is reversed at test transformer terminals 220 and 222. Output is not realized until DC is supplied to relay 348 in response to closure of program switch 318 under control of program spacer 644. Presence of program spacer 646 to actuate program switch 312 completes the low side energization of relay 348 which applies the test transformer output in the proper reversed phase. Program spacer 648 then closes programs switch 324 to effect test reset and, 2 seconds later, program spacer 650 effects closure of program switch 322 to verify the test condition.

Proper coordination with the A terminal carrier transmission is then made at the B terminal through switch closure by the program spacers 652 and 658. Comparisons of local and received signals are made at the terminals to verify the reception of alarms, but without the tripping conditions. These indications again must be verified or each tenninal will alarm and lockout, and the test will be stopped with alarms being reported to and stored at the master terminal test unit 150.

The B terminal program at position 45 then reverses the phase of its test source potential by keying program switches 474 and 476 by means of the program spacers 656 and 658. At this time all test potentials are again in phase. The simultaneous comparisons of local tripping conditions are made when the master remote switch 312 is keyed by the master A terminal program spacer 660, verification coming with closure of program switch 320 in response to program spacer 662. At the same time the remote program switch 472 is keyed in response to program spacer 664 with a verification by actuation of the program switch 480 in response to spacer 666. If at any time the units fail to obtain the proper starting signal, ring back, presence or absence of simulated faults along with the proper security codes; all units will alarm, lockout, stop testing and the proper alarm indications will be reported to the master terminal. The alarm indications, which may be repeated at some designated control center, must be personally ackowledged by an attendant and manually reset at the master terminal.

It should be fully understood that a test system constructed in accordance with the present invention is applied to selected test terminals or stations. Thus, a two or three tenninals automatic testing system can be installed for coactive operation at two or three terminals. The program 670 of FIG. 9 illustrates a three terminal program with proper program spacer arrays for each of tenninals A, B and C. Terminal A is the master terminal maintaining the control central and alarm functions while both of terminals B and C are made to slave to the master tenninal A.

FIG. 10 illustrates another form of commercially available transmission line surveillance network which can be tested with the automatic testing system of the invention. It should be understood too that various surveillance networks using different subcombinations of commercially available type are compatible with the present invention. In FIG. 10, the surveillance network 680 is a microwave transmission link shown installed between two terminals, including circuit breakers 682 and 684, along a powerline 686.

At circuit breaker 684, a control transformer 688 is located in sampling proximity to the powerline 686 to provide a sequence network output via connection 690 to a static relay 692. The static relay 692 would include a trip amplifier 694 and a connection 696 for breaking the circuit. The static relay 692 may take any of the various forms; however, the present application is directed mainly to the phase comparison type of relay. Thus, a suitable test source 698 may be energized by a key input 700 to provide a suitable test signal input to static relay 692, which static relay 692 is in coacting interconnection with a control unit 702 of conventional type. A low-set output from static relay 692 is utilized to key a tone transmitter 704 which, in turn, modulates a microwave transmitter/receiver 706, and also to supply an input control signal to control unit 702.

The microwave transmitter/receiver is a conventional UI-IF or SI-IF transmitter as utilized for telemetric purposes. Suitable microwave telemetric transmitter/receiver equipment is, for example, commercially available from the Leukurt Electric Co. of San Carlos, Calif. Energy received by the microwave transmitter-receiver 706 is applied to a tone receiver 708 which demodulates and applies its output to the control unit 702 to complete the control function. Suitable forms of tone receivers and transmitters, as may be employed for tone receiver 708 and tone transmitter 704, are Model MC22 which are commercially available from the Motorola Company of Chicago, Ill.

The other terminal 682 includes similar equipment. That is, a microwave transmitter/receiver 710 functions in coaction with a tone transmitter 712 and a tone receiver 714, each being interconnected to a control unit 716. An output from control unit 716 is applied to a trip amplifier 718 which is an integral component of a static relay 720. The static relay 720 is connected by means of the connection 722 to a control transformer 724 while maintaining a mechanical disabling connection 726 with the circuit breaker 682. The key input 728 and test source 730, similar to that at the other terminal or proximate the circuit breaker 684, are included with input interconnection to static relay 720.

Interconnection of the test equipment to carry out the various test, verify, alarm, etc. functions is easily carried out, interconnection being similar to that previously described in FIG. 5. Inputs and outputs relating to the prior carrier functions would be applied to the like components of the microwave transmitter/receiver system, and the control interconnection relating to the static relay, control unit and trip amplifiers would remain the same.

The foregoing discloses a novel automatic testing system for use in maintaining high voltage electrical transmission networks. The test system is capable of interconnection for coactive testing operation automatically and between any two or three terminal stations in a power distribution grid. In addition, the automatic test can be utilized with various forms of communication equipment, i.e. carrier equipment, microwave equipment, telephone hookup, etc. Testing may be effected in coaction with various types of the conventional protective relays such as directional, phase comparison, impedance directional comparison, conductance directional comparison, and combination whether solid-state or hard tube types.

While it is intended that circuit components utilized in the present invention may be of the time-proven types capable of heavy duty, long time operation with little or no maintenance, it is also contemplated that the entire system can be constructed from the more recently developed solid-state components. Such choices as to components and overall types of construction may be dictated by the exigencies of each particular application.

Changes may be made in the combination and arrangement of elements as heretofore set forth in the specification and shown in the drawings; it being understood that changes may be made in the embodiments disclosed without departing from the spirit and scope of the invention.

What is claimed is:

1. Apparatus for testing a plural terminal powerline protective relay system which includes a transmitter and receiver interconnected with a control unit and protective relay connected to control a line circuit breaker assembly at each terminal, each of the transmitter and receivers being in mutual communication, the apparatus comprising:

first programming switch means located at a first terminal and being actuatable to function for a predetermined duration;

first control means which is actuated by said first programming switch means to energize the first terminal transmitter to transmit carrier energy;

second programming switch means located at a second terminal and being actuatable to function for a predetermined duration;

second control means which is actuated by the second terminal receiver upon receiving the transmitted carrier energy from said first terminal to actuate said second programming switch means to function for said predetermined duration;

first and second auxiliary relay means located at respective first and second terminals and being energizable to remove said circuit breaker assembly from control con nection to said control unit and protective relay; and

first and second switching means controlled by respective first and second programming switch means to energize respective first and second auxiliary relay means during predetermined intervals of said predetermined duration.

2. Apparatus for testing a plural terminal powerline protective relays system as set forth in claim 1 which is further characterized to include:

third programming switch means located at a third tenninal and being actuatable to function for a predetermined duration;

third control means which is actuated by the third terminal receiver upon receiving transmitted carrier energy from said first terminal to actuate said third programming means to function for said predetermined duration;

third auxiliary relay means located at said third terminal and being energizable to remove the circuit breaker assembly from control connection to said third terminal control unit and protective relay; and

third switching means controlled by the third programming switch means to energize a respective third auxiliary relay means during predetermined intervals of said predetermined duration.

3. Relay system testing apparatus for use with electrical transmission lines having plural terminals each of which includes an interconnected transmitter and receiver, ad a phase comparison protective relay and control unit, which control unit includes means for keying a respective transmitter with alternating, discontinuous fault voltages in response to a fault condition at the respective terminal, the test apparatus compnsrng:

first means at a first local terminal for generating a first fault voltage which simulates a first trip condition;

second means at a second remote terminal for generating a second fault voltage which simulates a second trip condition;

verification means receiving each of said first and second fault voltages to determine phase relationship thereby to indicate a predetermined fault condition relative to said first and second tenninals; and

first and second program switch means automatically energized in synchronous relationship to actuate the respective first and second means simultaneously.

4. Testing apparatus as set forth in claim 3 which is further characterized to include:

first switch means actuated by said first program switch means to reverse the phase of said first fault voltage such that said verification means indicates a second predetermined fault condition.

5. Testing apparatus as set forth in claim 4 which is further characterized to include:

second switch means actuated by said second program switch means to reverse the phase of said second fault voltage such that said verification means indicates a different fault condition.

6. Test apparatus for use in testing a protective relay system functioning with an electrical transmission line wherein each of local and remote terminals interconnecting sald transmission line include a circuit breaker with trip circuitry to operate said circuit breaker upon reset fault indication, a transmission and receiver equipment, and a protective relay including control circuitry for keying said transmitter in response to locally detected fault indication signals and for comparing the phase of fault indication signal received from remote transmitters with the phase of fault indication signals generated at the local transmitter to determine if the fault is internal or external of the interconnecting transmission line, the test apparatus comprising:

program control means located at said local terminal and actuatable to efiect selected operation of a plurality of program switches at differing intervals through a predetennined time sequence, each of said switches being connected to provide a program control output actuation; starting means for actuating said program control means;

an electrical power supply;

auxiliary relay means connected to said circuit breaker trip circuitry to apply electrical power to said trip circuitry when said auxiliary relay means is deenergized such that the trip circuitry will operate said circuit breaker upon preset fault indication;

circuit means connecting a first program control output actuation of one of said plurality of program switches to energize said auxiliary relay means thereby to remove said electrical voltage to said trip circuitry to disable operation of said circuit breaker for the duration of said fist program control output actuation; and

fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said protective relay and control circuitry to key said transmitter and provide trip indication.

7. Test apparatus as set forth in claim 6 wherein said fault simulation means comprises:

transformer means connected to simulate a fault current indication as an AC electrical voltage; and

first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry. 8. Test apparatus as set forth in claim 7 which is further characterized in that:

fourth and fifth program control output actuations of said plurality of program switches are periodically actuated to reverse the phase of the output AC fault indication voltalge from said first rela means. 9. est apparatus as set orth in claim 6 wherein said remote terminal also includes test apparatus comprising:

remote program control means located at said remote terminal and being actuatable to effect selected operation of a plurality of program switches at difiering intervals through a predetermined time sequence, each of said switches being connected to provide a program control output actuation; carrier relay means responsive to transmission from said transmitter at the local terminal to start actuation of said remote program control means; a remote electrical power supply; remote auxiliary relay means connected to said remote circuit breaker trip circuitry to apply electrical power to said remote trip circuitry when said remote auxiliary relay means is deenergized such that the remote trip circuitry will operate said remote circuit breaker upon preset fault indication; remote circuit means at the remote station connecting a first program control output actuation of one of said plurality of program switches of the remote program control means to energize said remote auxiliary relay means thereby to remove said electrical voltage to said remote trip circuitry and to disable operation of said remote circuit breaker for the duration of said first program control output actuation; and remote fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said remote protective relay and control circuitry to key said remote transmitter and provide a remote trip indication. 10. Test apparatus as set forth in claim 9 wherein said remote fault simulation means comprises:

transformer means connected to simulate a fault current indication as an AC electrical voltage; and first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry. 11. Test apparatus as set forth in claim 10 which is further characterized to include:

fourth and fifth program control output actuations of said plurality of program switches are periodically each actuated to reverse the phase of the output AC fault indication voltage from said first relay means. 12. Test apparatus as set forth in claim 6 wherein said starting means comprises:

synchronous motor means mechanically coupled with an electrical switch means, said motor means functioning to close said switch means at periodic intervals. 13. Test apparatus as set forth in claim 9 which is further characterized in that:

said starting means at the local terminal consists of an electrical switch closed at periodic intervals by a synchronous timing motor, and said remote terminal starting means is a relay means energized in response to receipt of carrier from the local transmitter to start a cycle of test operation at the remote terminal. 

1. Apparatus for testing a plural terminal powerline protective relay system which includes a transmitter and receiver interconnected with a control unit and protective relay connected to control a line circuit breaker assembly at each terminal, each of the transmitter and receivers being in mutual communication, the apparatus comprising: first programming switch means located at a first terminal and being actuatable to function for a predetermined duration; first control means which is actuated by said first programming switch means to energize the first terminal transmitter to transmit carrier energy; second programming switch means located at a second terminal and being actuatable to function for a predetermined duration; second control means which is actuated by the second terminal receiver upon receiving the transmitted carrier energy from said first terminal to actuate said second programming switch means to function for said predetermined duration; first and second auxiliary relay means located at respective first and second terminals and being energizable to remove said circuit breaker assembly from control connection to said control unit and protective relay; and first and second switching means controlled by respective first and second programming switch means to energize respective first and second auxiliary relay means during predetermined intervals of said predetermined duration.
 2. Apparatus for testing a plural terminal powerline protective relays system as set forth in claim 1 which is further characterized to include: third programming switch means located at a third terminal and being actuatable to function for a predetermined duration; third control means which is actuated by the third terminal receiver upon receiving transmitted carrier energy from said first terminal to actuate said third programming means to function for said predetermined duration; third auxiliary relay means located at said third terminal and being energizable to remove the circuit breaker assembly from control connection to said third terminal control unit and protective relay; and third switching means controlled by the third programming switch means to energize a respective third auxiliary relay means during predetermined intervals of said predetermined duration.
 3. Relay system testing apparatus for use with electrical transmission lines having plural terminals each of which includes an interconnected transmitter and receiver, ad a phase comparison protective relay and control unit, which control unit includes means for keying a respEctive transmitter with alternating, discontinuous fault voltages in response to a fault condition at the respective terminal, the test apparatus comprising: first means at a first local terminal for generating a first fault voltage which simulates a first trip condition; second means at a second remote terminal for generating a second fault voltage which simulates a second trip condition; verification means receiving each of said first and second fault voltages to determine phase relationship thereby to indicate a predetermined fault condition relative to said first and second terminals; and first and second program switch means automatically energized in synchronous relationship to actuate the respective first and second means simultaneously.
 4. Testing apparatus as set forth in claim 3 which is further characterized to include: first switch means actuated by said first program switch means to reverse the phase of said first fault voltage such that said verification means indicates a second predetermined fault condition.
 5. Testing apparatus as set forth in claim 4 which is further characterized to include: second switch means actuated by said second program switch means to reverse the phase of said second fault voltage such that said verification means indicates a different fault condition.
 6. Test apparatus for use in testing a protective relay system functioning with an electrical transmission line wherein each of local and remote terminals interconnecting said transmission line include a circuit breaker with trip circuitry to operate said circuit breaker upon reset fault indication, a transmitter and receiver equipment, and a protective relay including control circuitry for keying said transmitter in response to locally detected fault indication signals and for comparing the phase of fault indication signal received from remote transmitters with the phase of fault indication signals generated at the local transmitter to determine if the fault is internal or external of the interconnecting transmission line, the test apparatus comprising: program control means located at said local terminal and actuatable to effect selected operation of a plurality of program switches at differing intervals through a predetermined time sequence, each of said switches being connected to provide a program control output actuation; starting means for actuating said program control means; an electrical power supply; auxiliary relay means connected to said circuit breaker trip circuitry to apply electrical power to said trip circuitry when said auxiliary relay means is deenergized such that the trip circuitry will operate said circuit breaker upon preset fault indication; circuit means connecting a first program control output actuation of one of said plurality of program switches to energize said auxiliary relay means thereby to remove said electrical voltage to said trip circuitry to disable operation of said circuit breaker for the duration of said first program control output actuation; and fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said protective relay and control circuitry to key said transmitter and provide trip indication.
 7. Test apparatus as set forth in claim 6 wherein said fault simulation means comprises: transformer means connected to simulate a fault current indication as an AC electrical voltage; and first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry.
 8. Test apparatus as set forth in claim 7 which is further characterized in that: fourth and fifth program control output actuations of said plurality of program switches are periodically actuated to reverse the phase of the output AC fault indication voltage from saId first relay means.
 9. Test apparatus as set forth in claim 6 wherein said remote terminal also includes test apparatus comprising: remote program control means located at said remote terminal and being actuatable to effect selected operation of a plurality of program switches at differing intervals through a predetermined time sequence, each of said switches being connected to provide a program control output actuation; carrier relay means responsive to transmission from said transmitter at the local terminal to start actuation of said remote program control means; a remote electrical power supply; remote auxiliary relay means connected to said remote circuit breaker trip circuitry to apply electrical power to said remote trip circuitry when said remote auxiliary relay means is deenergized such that the remote trip circuitry will operate said remote circuit breaker upon preset fault indication; remote circuit means at the remote station connecting a first program control output actuation of one of said plurality of program switches of the remote program control means to energize said remote auxiliary relay means thereby to remove said electrical voltage to said remote trip circuitry and to disable operation of said remote circuit breaker for the duration of said first program control output actuation; and remote fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said remote protective relay and control circuitry to key said remote transmitter and provide a remote trip indication.
 10. Test apparatus as set forth in claim 9 wherein said remote fault simulation means comprises: transformer means connected to simulate a fault current indication as an AC electrical voltage; and first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry.
 11. Test apparatus as set forth in claim 10 which is further characterized to include: fourth and fifth program control output actuations of said plurality of program switches are periodically each actuated to reverse the phase of the output AC fault indication voltage from said first relay means.
 12. Test apparatus as set forth in claim 6 wherein said starting means comprises: synchronous motor means mechanically coupled with an electrical switch means, said motor means functioning to close said switch means at periodic intervals.
 13. Test apparatus as set forth in claim 9 which is further characterized in that: said starting means at the local terminal consists of an electrical switch closed at periodic intervals by a synchronous timing motor, and said remote terminal starting means is a relay means energized in response to receipt of carrier from the local transmitter to start a cycle of test operation at the remote terminal. 